In the circuit below a battery of UNKNOWN emf and an internal resistance of 0,5 Ω is connected to two resistors of 4 Ω and 8 Ω each, and a resistor R of unknown resistance.
Ignore the resistance of the connecting wires.
8.1 The three external resistors are ohmic conductors.
Explain the meaning of the term ohmic conductor. (2)
8.2 When switch S is OPEN, voltmeter V1 reads 3,2 V.
8.2.1 Current through the battery (3)
8.2.2 Emf of the battery (4)
8.3 When switch S is CLOSED, voltmeter V2 reads 8,8 V.
8.3.1 Calculate the resistance of resistor R. (5)
8.3.2 The battery becomes heated when voltmeter V2 is replaced by a connecting wire. Explain this observation. (3)